tagged w/ Chromosomes
-
Blood tests that seek to tell people their biological age — possibly offering a clue to their longevity or how healthy they will remain — are now going on sale. But contrary to various recent media reports, the tests cannot specify how many months or years someone can expect to live.
:http://www.nytimes.com/2011/05/19/business/19life.html?ref=technologyBlood tests that seek to tell people their biological age — possibly offering a... more
-
-
Plants adapt to the local weather and soil conditions in which they grow, and these environmental adaptations are known to evolve over thousands of years as mutations slowly accumulate in plants' genetic code.
:http://www.sciencedaily.com/releases/2011/05/110503151605.htmPlants adapt to the local weather and soil conditions in which they grow, and these... more
-
-
suzane
-
added this
-
1 year ago
- |
-
Theoretical physicists have proposed an explanation for how bacteria might transmit electromagnetic signals: Chromosomes could act like antennae, with electrons traveling gene circuits to produce species-specific wavelengths.
link: http://www.wired.com/wiredscience/2011/04/bacterial-radio/Theoretical physicists have proposed an explanation for how bacteria might transmit... more
-
-
eva2
-
added this
-
1 year ago
- |
-
Genetic research has mainly centered around the Y-chromosome and mDNA, which are used most frequently when tracing both ancient and historical human migrations. Now, looking at the X-chromosome, [Geneticists] believe they have perfected a way of using the X-chromosome to unravel details about the initial migration of humans out of Africa tens of thousands of years ago.
One of the reasons analysis of the X-chromosome has not proven straightforward is that the way the X is passed down from one generation to the next differs depending on the sex of the child. Fathers pass on their X-chromosomes to their daughters, but not their sons, while mothers pass one X-chromosome to their children of both sexes. So while any person’s X-chromosome came down to them along a specific lineage — just like their Y-chromosome and mDNA — that path is impossible to trace.
The National Human Genome Research Institute analyzed the genotypes of people from around the globe and looked for differences among the populations of Africa, Europe and East Asia. Though they found the expected 75% X-chromosome diversity ratio within Africans, there was considerably less diversity among European and East Asians on the X compared to their 22 non-sex chromosomes.
A decrease in genetic variation is usually a sign of decreased population size. Because it shows up in East Asians and Europeans but not Africans, it is believed that the decreased variation is a signal of a population bottleneck that occurred after humans left Africa for the first time nearly 60,000 years ago.
However, the decreased genetic variation only seems to show up on the X-chromosome. This, the authors speculate, may be due to some sort of sex-biased migration. In other words, when humans first ventured outside of Africa and into Europe and Asia, there may have been more men on the move than women. Scientists have long observed the same phenomenon when comparing the Y-chromosome to mDNA; now researchers are seeing the same phenomenon here, with the X.Genetic research has mainly centered around the Y-chromosome and mDNA, which are used... more
-
-
Atlanta policewoman understands at last why her voice is deep, why she’s attracted to women and why she can grow a full beard. And she’s OK with it.
Harris is intersex — someone whose internal or external sexual anatomy or chromosomes don’t fit the typical definitions of female or male at birth or puberty, according to Sharon Preves, a sociology professor and intersex researcher from St. Paul, Minn.
Genetic testing recently revealed that Harris carries the XY chromosomes of a male while having external sexual anatomy that appears to be a blend of a man’s and woman’s.
“It was like, ‘OK, I’m not crazy,’ ” said Harris, 35, who was identified as a female at birth and has lived her adult life as a lesbian, feeling like a man in a woman’s body.
An estimated 1 in 2,000 people are considered intersex, and numerous medical conditions cause it, said Preves, who wrote the book, “Intersex and Identity: the Contested Self,” in 2003.
People become intersex when they have overactive or under active hormones or the inability to respond to hormones during fetal development, Preves said.
For the past three years, Harris has been the Police Department’s liaison to the gay, lesbian, bisexual and transgender communities. She works with those who are victims of hate crimes or who file complaints against police officers. She also gives speeches for groups or organizations in those communities.
Harris said she has never had a problem with anyone in the Police Department while she identified as a lesbian. And no one has had a cross word for her since she went public about being intersex.
She said that her supervisor, Maj. Pearlene Williams, took a supportive role as she went from doctor to doctor. Once Harris learned she had male chromosomes, she said she broke down and cried in Williams’ office.
We’re living in a society where there are only two choices for anatomy, even though there are so many variations,” Preves said.
Numerous variations considered intersex include:
• A person who has female chromosomes but external male genitalia.
• A person who has male chromosomes but external female genitalia.
• A person who is internally male or female, but has ambiguous external genitalia, such as a noticeably large clitoris that resembles a small penis.
It wasn’t until Harris started dating her current girlfriend in late 2007 that she went to a gynecologist to explore the differences in her body and, in turn, her anger issues.
That visit led Harris to an endocrinologist, who ran a chromosome test in February that offered medical proof to support how she feels: like a man in a woman’s body.
The news made Harris weep.
“It has lifted the burden off me and also released a lot of the anger,” Harris said. “I was angry and I couldn’t understand why.”
Harris said she thought about having a sex change to male, but decided against it.
“For what?” she asked. “God doesn’t make mistakes. I’m just uniquely different.”
She has quickly found peace being somewhere in the middle.Atlanta policewoman understands at last why her voice is deep, why she’s... more
-
-
Previous research suggested that prehistoric people in eastern and southern Africa had little contact, with only two known migrations between the regions about 30,000 and 1,500 years ago. After Bantu-language speakers migrated from eastern to southern Africa 1,500 years ago, agriculture took off in southern Africa. But the timing of the Bantu migration didn't quite match the 2,000-year-old anthropological evidence for the first sheep and cattle herds in southern Africa, so anthropologists were unsure whether the region's agricultural knowledge came from a bow-wave of ideas that spread in front of the migrating Bantu, or whether a separate migration brought the first herders.
"Africa has the most genetic diversity in the world, but it is one of the least-studied places," said Brenna Henn, a doctoral student in anthropology who was the study's lead author. "I've always felt like there were a lot of stories there that nobody's had the time or interest to look into."
The Stanford scientists picked the Y sex chromosome to examine for clues to migration because it changes very little from one generation to the next. Autosomes—the non-sex chromosomes—come in pairs, and the members of a pair can exchange bits of DNA during reproduction, making each autosome a mishmash of DNA from all of an individual's ancestors. But the Y chromosome is a singleton; males inherit one Y and one X chromosome, while women have two X chromosomes. In men, only a tiny region of the Y chromosome swaps DNA with the X chromosome. This means almost all of the Y chromosome moves intact from father to son, changing only infrequently when a new genetic mutation arises. That allows researchers to examine several generations of ancestry by looking at the Y chromosomes of living men.
"The family tree of the Y chromosome is very, very clear," Mountain said.
The team analyzed Y chromosomes from men in 13 populations in Tanzania in eastern Africa and in the Namibia-Botswana-Angola border region of southern Africa. They discovered a novel mutation shared by some men in both locations, which implied those men had a common ancestor. Further analysis showed the novel mutation arose in eastern Africa about 10,000 years ago and was carried by migration to southern Africa about 2,000 years ago. The mutation was not found in Bantu-speakers, suggesting that a different group—Nilotic-language speakers—first brought herds of animals to southern Africa before the Bantu migration.
This new genetic evidence correlates well with pottery, rock art and animal remains that suggest pastoralists—herders who migrated to new pasture with their flocks—first tended sheep and cattle in southern Africa around 2,000 years ago. The genetic finding also helps explain linguistic similarities between peoples in the two regions.
"I like the fact that the linguistic, genetic and archaeological evidence all line up," Henn said. "When you see lines of evidence converge on a single model, it means that's probably something that actually happened." Previous research suggested that prehistoric people in eastern and southern Africa had... more
-
-
The rapid growth of companies offering personal genetic DNA tests has prompted officials in California and New York to start investigation into the legality and accuracy of these services.The rapid growth of companies offering personal genetic DNA tests has prompted... more
-
-
Jael
-
added this
-
4 years ago
- |
-
Experts say that our level of happiness is 'strongly influenced by the genes with which we were born'. Based on a study of twins (oh, twins, the human guinea pigs), genes may control as much as 50 percent of the personality traits that keep us feeling good. The rest is influenced by lifestyle, career and relationships. That doesn't mean some of us are doomed to be half-happy forever. Another expert claims that despite the findings of this study, we can still train ourselves to be more content.Experts say that our level of happiness is 'strongly influenced by the genes with... more
-
-
Telomeres, the supposedly "dead" sections of DNA that cap the ends of chromosomes, are showing definite signs of life. Telomeres shorten every time a cell divides until they reach a critical length - at which point the cell dies through a process called apoptosis. Cancers sometimes develop when the telomerase enzyme gets switched on and rebuilds the telomeres, making the cells immortal.Telomeres, the supposedly "dead" sections of DNA that cap the ends of... more
-
